Furnace blower installation



H; E. HOFVENDAHL v 3,486,688

FURNACE BLOWER INSTALLATION Dec. 30, 1969v 3' Sheets-Sheet 2 Filed June20, 1968 Fig.4

INVENTOR.

Attorneys 5 Sheets-Sheet 5 Dec. 30, 1969 H. E. HQFVENDAHL FURNACE BLOWERINSTALLATION Filed June 20. 1968 F I g I I B HerberrE United StatesPatent 3,486,688 FURNACE BLOWER INSTALLATION Herbert E. Hofvendahl, 6Corte Sombrita, Orinda, Calif. 94563 Filed June 20, 1968, Ser. No.738,451 Int. Cl. F04b 39/00; F16m 1/04 US. Cl. 230-235 12 ClaimsABSTRACT OF THE DISCLOSURE A blower installation for mounting a base ofthe blower to a bulkhead or other support structure of forced airfurnaces and air conditioners is disclosed. The base includes parallel,spaced flanges which rest on elongate, parallel rails or bearing memberssecured to a resilient, oscillation dampening material mounted on thebulkhead to prevent the transfer of vibrations from the blower to thebulkhead and the support structure. The blower base can be slideablyengaged with the rails to facilitate the ease with which the blower isplaced on and removed from the bulkhead. A plurality of spaced arms aresecured to the bulkhead and the blower base, which arms have at theirfree ends resilient bumpers mounted thereon which engage the bulkhead orthe base in an oscillation dampening manner and which prevent relativemovement of the base away from the supporting rails while permittingslideable relative movements between the flanges of the base and therails of the bulkhead. Means are preferably also provided fordemountably and flexibly securing the base to the bulkhead withouttransferring vibrations from the blower to the bulkhead.

BACKGROUND OF THE INVENTION The present invention relates to blowerinstallations and more particularly to such installations which mountthe blower in a furnace, air conditioner or other heating or airconditioning equipment in a vibration dampening manner while permittingslideable movement between the blower and such equipment to place theformer in or remote it from such equipment.

Conventional forced air furnaces provide a housing which is partitionedby a bulkhead into a heat exchanger chamber, containing a heat exchangeunit, and a fresh air supply chamber, housing a motor operated impelleror blower for supplying fresh air into the heat exchanger of thefurnace. The bulkhead includes an opening over which the blower ismounted and through which the fresh air enters the heat exchange chamberof the housing. To facilitate the ease with which the blower isinstalled or removed during the initial assembly of the furnace and forsubsequent maintenance and repair work, prior art furnaces have beendevised which mount the blower on parallel, elongate rails secured to orforming an integral part of the bulkhead. The blower includes flangeswhich rest on the rails and thus support it on the bulkhead.

During operation of the furnace, the impeller of the blower rotates at arelatively high speed and causes substantial vibrations. Ordinarily thevibrations are transmitted to the furnace structure which causesexcessive and disturbing noise. The noise is frequently transmittedthrough heating ducts connecting with the furnace to remote rooms of thebuilding or house in which the furnace is installed. To reduce theadverse efiects of the blower vibrations, it has been suggested to placethe blower on rails or bearing members which are isolated from thebulkhead by resilient materials. Such a blower installation is disclosedin US. Patent No. 2,464,473.

The installation disclosed in the above referred to patent substantiallyreduces the adverse effect from blower vibrations. The blower, however,rests on the support rails by its own weight and no provisions are madeto secure it to the supporting bulkhead since a fixed interconnectionbetween the bulkheads and the blower substantially reduces thebeneficial effects obtained from the resilient mounting of the blower.To positively secure the blower to the resiliently mounted rail orbearing member is difficult or impossible without losing the advantagesobtained from the sildeable interengagement of the flanges of the blowerand the rails of the bulkhead. Consequently, the blower can vibrate sothat the flanges alternately become disengaged and then engaged with therails. The resiliently mounted rails have a tendency to accentuate suchmovement or vibrations of the blower which can result in damage to thefurnace or the blower and in excessive noise.

Another technique which has previously been used is to mount the blowerson relatively large rubber blocks secured to the support structure.Excellent results have been obtained with such installations since theydampen the vibrations and virtually eliminate noise therefrom. However,it is a relatively expensive blower installation both in terms of itsinitial cost and the cost of disassembling the blower from the mounts.Its use is, therefore, limited to large, industrial blowers for furnacesor cooling units servicing large buildings.

Thus, the prior art does not provide fully satisfactory low costinstallations for furnace blowers.

SUMMARY OF THE INVENTION The present invention provides a low cost,vibration dampening which positively constrains the blower to thesupport structure of the equipment in which it is mounted. Briefly, theinstallation comprises a support structure, resilient means secured tothe structure and a support rail or bearing member secured to theresilient means for dampening vibrations of the rail when subjected tocyclical forces from the blower. The blower includes a mounting flangeextending from the blower and slideably contacting the rail forsupporting the blower on the rail. Holding means interengaging thesupport structure and the blower are provided for preventing thedisengagement nf the flange and the rail and for dampening vibrationalmovement of the flange while the blower is in operation.

The blower installation of the present invention is adapted for use inconjunction with all furnaces, air conditioners, and heating equipment(herein referred to as furnaces) having a bulkhead between two furnacechambers, irrespective of whether the blower is mounted above or belowthe heat exchanger of the furnace. The holding means preferably comprisea plurality of spaced arms secured to the blower base or the bulkheadssupporting the blower and having at their free ends resilient parts toprovide the interconnection between the blower and the bulkhead. Theresilient parts and the arms are formed to prevent all movements of theblower, in response to vibrations of its impeller, away from thesupporting rails and to simultaneously enable the slideable engagementof the blower with the support rails of the bulkhead. The advantages ofan easy, effortless and time saving installation and removal of theblower are thereby retained while the transfer of undesirablevibrational movement from the blower to the bulkhead and the remainingsupport structure have been eliminated. This permits a virtuallynoiseless operation of the furnace.

The present invention employs simple, mass produceable and, therefore,inexpensive parts to subdue the vibrations of the blower. The assemblyand installation of the vibration dampening components is easy andquickly performed and is, therefore, economical. The advantages of anoise free operation and a positive mounting of the blower are thus, forthe first time, available on low cost,

home type furnaces. In addition, this invention enables prior artfurnaces to be equipped with the vibration dampening means.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a front elevational viewof a counter flow furnace having a blower installed on top of its heatexchanger in accordance with the present invention;

FIGURE 2 is a side elevational view taken on line 22 of FIGURE 1;

FIGURE 3 is a plan view, in section, taken on line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary, enlarged view, in section, taken on line 4-4of FIGURE 3;

FIGURE 5 is a fragmentary, enlarged view, in section, taken on line 55of FIGURE 3;

FIGURE 6 is a fragmentary plan view, in section similar to FIGURE 3 andshowing another embodiment of this invention;

FIGURE 7 is a fragmentary, enlarged view, in section, taken on line 77of FIGURE 6;

FIGURE 8 is a front elevational view, similar to FIG- URE 1, of anupflow furnace having a blower installed in accordance with the presentinvention;

FIGURE 9 is a bottom view, in section, taken on line 99 of FIGURE 8;

FIGURE 10 is a fragmentary, enlarged cross sectional view taken on line1010 of FIGURE 9; and

FIGURE 11 is a fragmentary, enlarged, cross sectional view taken on line1111 of FIGURE 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGURES 1 and 2, acounter flow furnace 12 comprises a housing 14 divided by a bulkhead 16into an upper fresh air intake chamber 18 and a lower heat exchangerchamber 20. Mounted in the heat exchanger chamber is a burner 22 whichcommunicates with a heat exchanger 24 and a flue 26 through whichexhaust gases from the burner are discharged. Although the presentinvention is described in conjunction with a warm air furnace, it is asabove indicated used with equal success for air coolers. In such a case,the burner is replaced by a cooling or refrigeration unit (not shown)which communicates with the heat exchanger.

Fresh air intake chamber 18 communicate with the exterior of the furnacethrough a filter element (not shown) and houses a blower 30 which issecured to bulkhead 16. The blower includes an intake opening 32 androtatably mounts an impeller 34 driven by an electric motor 36 via belt28. Alternatively, a motor connected directly to the impeller may beprovided.

Referring to FIGURES 3 through '5, bulkhead 16 is defined by fourrectangularly shaped sheet metal sections 40, 41, 42 and 43, which maybest be seen in FIGURE 3, and these sections define an opening 44 in thebulkhead communicating the fresh air intake chamber of the furnace withthe heat exchanger chamber thereof. Ends 45 of sheet metal sections 41and 42 defining the opening in the bulkhead are Z-shaped and offset (seeFIGURE 4) and support an elongate strip 46 of a resilient material, suchas plastic foam or foam rubber. Alternatively, strip 46 may be replacedby a leaf spring formed of spring steel, coil springs or other types ofsprings formed of various material. The elongate strips are preferablybonded to Z- shaped ends 45 and support elongate, L-shaped bearingmembers or rails 48 bonded to the strips of resilient material. Thus,the rails are parallel, and spaced from each other and preferably extendover the full length of the sheet metal sections.

The sheet metal sections of the bulkhead are a portion of the supportstructure of the furnace and are secured to side panels 50 defininghousing 14 of the furnace. A front panel 52 (FIGURE 2) is demountable toprovide access to blower 30. Upon removal of front panel 52, flue 26 canbe pulled down and out of bulkhead 16 and the blQWer removed. The bloweris mounted on a base 54 which has a width about equal to the spacingbetween the L-shaped rails 48 and which includes parallel angles 56having flanges 58 of a length equal to that of the L-shaped rails. Thebase, and the blower, is installed in the furnace by placing the flangesof the angles on top of L-shaped rails 48 and slideably moving the baseand the blower relative to the rails until a forward end 60 of theangles engages the interior sheet 43 of the bulkhead 16. In the past, noadditional means for connecting the base and the blower to the bulkheadsof the furnace were provided. The base was simply left in this position,the motor was connected with a source of electric power and operated.This resulted in the above referred to vibrational movements of the baseoff the resiliently mounted L-shaped rails 48.

To constrain the base and the blower to the bulkhead and minimize orprevent virbational movement of the base while the blower is inoperation, a pair of elongate arms 64 are secured to sheet metalsections 41 and 42 adjacent rear panel 51 of the housing 14. Free ends66 of the arms have mounted thereon resilient bumpers 68 with rivets 70or by bonding the bumpers to the arms. The bumpers are preferablycylindrical or frusto-conically shaped, commercially available rubberbumpers to minimize their cost. In the alternative, however, the bumpersmay have any other desired configuration. End faces 72 of the bumpersare directed toward the adjacent L-shaped rails 48 and are spacedtherefrom a distance about equal to the thickness of flanges 58 ofangles 56 secured to base 54. To increase the vibration dampeningeffectiveness of bumpers, they are preferably positioned so that theirspacing from the L-shaped rails is slightly less than the thickness ofthe flanges of the angles to provide for an interference between therails, the end faces of the bumpers, and the flanges when the base andthe blower are supported by bulkhead 16.

Referring to FIGURES 3 and 5, a pair of Z-shaped arms 74 are secured toa forward end 75 of base 54. Arms 74 and rubber bumpers 68 are mountedfor engagement of their end faces 72 with sheet metal section 40 ofbulkhead 16. The Z-shaped arms extend past the bumpers to allow mountingof threaded bolts 78 or sheet metal screws through a bore (not shown) insheet metal section 40. The Z-shaped members, base 54 and blower 30, arethereby flexible connected with the bulkhead to prevent relative slidingmotions between the base and the L-shaped rails without transmittingvibrations from the base to the bulkhead. When bolts 78 or screws areemployed, the ends 76 of arms 74 afford a flexible connection betweenthe bulkhead and blower in that the inherent resiliency in arm 76, ascantilevered from base 54, allows movement of the base 54 relative tobulkhead 16. The Z-shaped arms and the bumpers mounted thereon providefurther vibration dampening support for the base and the blower.

In use, and when impeller 34 vibrates due to its imperfectly balancedmass, a base 54 is at all times maintained in firm contact with bulkhead16 through the vibration dampening strips 46 on the one hand and thevibration dampening bumpers 68 on the other hand. The base can neithermove up nor down relative to the bulkhead without depressing either theresilient strip or the resilient bumpers. The depression of theresilient materials minimizes or eliminates the transfer of vibrationalmovements of the blower and the base to the remainder of the furnace.Noise as well as vibrational movements of portions of the furnace, suchas bulkhead 16, are virtually eliminated.

Referring to FIGURES 6 and 7, another embodiment for the mounting ofblower 30 in a counterfiow furnace is illustrated. Bulkhead 16a isconstructed identically to bulkhead 16 shown in FIGURE 3 and comprisessheet metal sections 40a, 41a, 42a and 43a. Sections 41a and 42a includestrips 46a of a resilient material and L- shaped rails 48a bonded to thestrips. Pairs of arms 80, constructed similarly to arms 64 shown inFIGURES 3 through 5, are secured to sheet metal sections 41aand 42aadjacent their respective ends. Rubber bumpers 82 face toward flanges58a of angles 56a to secure the base and the blower to the bulkheads inthe same manner as do arms 64 and 74. In FIGURE 7 it will be noted thatthe surface of member 48a is flush with the surface of sheet metalsection 4011 so that the flange 58a can be slid over fixed member 40aunder the bumper 82. In FIG- URE 5, by contrast the top surface ofmember 48 is not on the same level as member 40, but the constructionand location of arms 74 allows for such a stepped relationship betweenthe surfaces. A similar stepped construction can be achieved in theblower mount of FIG- URES 6 and 7 if front arms 80 are demountablyattached to sections 41a and 4201 after the blower is slid intoposition.

Referring to FIGURE 8, an upflow furnace 86 is illustrated whichincludes an upper heat exchanger chamber 87 and a lower fresh airchamber 88 which are separated by a bulkhead 90. Burner 91 and a heatexchanger 92 are disposed in the upper chamber of the furnace while thelower chamber houses a blower 94 having an impeller (not shown in FIGURE8) driven by an electric motor 95 via a belt 96. In contrast to thecounterflow furnace shown in FIGURE 1, blower 94 is suspended frombulkhead 90 and hangs downwardly thereof. The blower draws fresh airthrough a filter unit (not shown in FIG- URE 8), forces it past heatexchanger 92 and into ducts (not shown).

Referring to FIGURES 9 through 11, bulkhead 90 is formed by four sheetmetal sections 98, 99, 100 and 101 which define an opening 102connecting the heat exchanger chamber of the furnace with the fresh airchamber. The sheet metal sections are secured to side panels 104 of thefurnace and a removable front panel provides access to opening 102 andthe blower.

Free ends 103 of sheet metal sections 99 and 100 are Z-shaped, in amanner similar to ends 45 of sections 41 and 42, shown in FIGURES 3 and4, and include a strip 108 of a resilient material bonded thereto.L-shaped rails 110 are bonded to the upper side of the strips ofresilient material and support flanges 112 of elongated, space apartangles 114 secured to a blower mounting base 116. Again, in accordancewith the prior art, the blower and the base mounting it are retained onthe L-shaped rails by their own weight. This results in noise andpossible damage to the furnace from the vibrating blower.

To minimize and eliminate vibrations of the operating blower sheet metalarms 118 are secured to an upper side 120 of sections 99 and 100 andhave free ends formed to project over flanges 112 supported by L-shapedrails 110. Rubber bumpers 122 are mounted on arms 118 facing toward andengaging the flanges in the above described manner.

In addition, Z-shaped brackets 124 are secured to base 116 adjacent itsend 126 which is adjacent the front opening in the fresh air chamber andare arranged to project outwardly and downwardly of the base over an endportion 128 of sheet metal sections 99 and 100. The brackets have rubberbumpers 123 mounted thereon at their central portion and are shaped sothat end faces 129 of the bumpers engage the end portions 128 of thesheet metal sections, thereby biasing flanges 112 of angles 114 intoengagement with L-shaped rails 110. In this manner, vibrational movementof base 116 while blower 94 operates are dampened and minimized tovirtually eliminate attendant noise.

As may best be seen in FIGURE 9, sheet metal panel 101 overlaps thefront end 126 of the blower base 116. Accordingly, the furnace blowermount of the present invention may be constructed by eliminating bumpers123 and 133 and positioning a bumper (not shown) on the top side of base116 so as to engage the bottom surface of panel 101.

It is often desirable to connect the blower with the supportingstructure of the furnace. For this purpose, an L-shaped bracket 130projects from the underside of sheet metals sections 99 and of bulkhead90 opposite a vertical end portion 132 of Z-shaped brackets 124 having aresilient bumper 133 mounted thereon. A threaded bolt 134 connects theL-shaped bracket and the vertical portion of bracket by urging bracket130 against bumper 133. The ability of bolt 134 to move transversely ofits longitudinal axis and bumper 133 to shift relative to bracket 130affords a flexible connection which also prevents a direct metal tometal contact and transmission of vibrations from the blower to thebulkhead, as would be the case if the two brackets were tightly securedto each other. The effectiveness of the vibration absorbing installationof this invention is thereby maintained It should be noted that in allembodiments of this invention the blower mounting base, and moreparticularly the angles supporting the base on the resiliently mountedL-shaped rails of the bulkheads, is firmly urged by vibration absorbingmembers against vibration away from the rails. Uncontrolled motions ofthe vibrating blower and base are, therefore, not possible. At the sametime, this invention retains the time saving and economic slideablemounting of the base on the bulkhead of the furnace. Aside from itsabove described general utility, this inven tion also enables thelow-cost rebuilding of prior art furnaces, which have blowers supportedon the bulkheads by their weight only, into furnaces wherein the blowersare positively constrained to the bulkheads. The task requires no morethan the installation of the arms carrying the resilient bumpers orbumpers alone so that the latter cooperate with the blower, or the base,and the bulkhead, including the L-shaped rails.

I claim:

1. A blower installation comprising, a support structure including anelongate rail, resilient means intermediate the structure and the railfor absorbing vibrations of the rail when subjected to cyclical forcesand a bulkhead; a blower including an elongate mounting flange slideablycontacting the support rail to support the blower on the rail; andholding means interengaging the support structure and the blower toprevent the disengagement of the flange and the rail and to absorbvibrational movement of the flange in a direction away from the rail.

2. A blower installation aceording to claim 1, including demountablemeans for securing the blower to the support structure to preventrelative slideable motions between them, the demountable means beingconstructed to prevent direct contact between a portion of the blowerand the support structure.

3. A blower installation according to claim 1, wherein the holding meanscomprise an arm and a resilient part secured to the arm and engaging aportion of the blower.

4. A blower installation according to claim 3, wherein the holding meanscomprises a plurality of spaced arms adjacent overlapping portions ofthe blower and the support structure.

5. A blower installation according to claim 1, wherein the holding meanscomprise arms secured to the support structure and extending over therail in a spaced relation therefrom, and a resilient part mounted on thearms to face the rail and engage the flange to absorb relative motionsof the flange away from the rail.

6. A blower installation according to claim 5 including additional armssecured to the blower and extending over the support structure in aspaced relation, and resilient parts secured to the additional arms toface and engage the support structure and absorb relative motion of theblower.

7. A blower installation according to claim 6, wherein the additionalarms and resilient parts are mounted adjacent the flange and arranged topermit the rails and the resilient means to be disposed intermediate theflange and the additional arms.

8. A blower installation according to claim 6, wherein the blowerincludes a pair of spaced apart, parallel flanges on sides of the blowerand the additional arms and resilient parts engage a side of the supportstructure which is transverse to said flanges.

9. A blower installation according to claim 6 including means forflexibly securing the blower to the support structure and for preventingrelative slideable movement between them.

10. A blower installation comprising (a) a support structure,

(b) a pair of parallel support rails mounted on the structure andisolated therefrom by resilient, vibration absorbing means,

(0) a blower base including parallel spaced apart flanges formed toslideably engage and support the blower on the rails,

(d) holding means including a plurality of spaced apart arms mountingresilient parts which interconnect the base with the support structurefor preventing movement of the flanges away from the rails in avibration absorbing manner, the arms and the resilient parts beingformed to permit the slideable interengagement of the flanges, the railsand the resilient means, and

(e) means for demountably securing the base to the support structure toprevent relative sliding motion between them.

11. A blower installation according to claim 10, wherein the blower issuspended from and positioned below the rails and the holding meanscooperate and are in engagement with the rails and the flanges.

12. A blower installation according to claim 10, wherein the blower ispositioned above the rails, some of the arms and resilient partscooperate with the rails and the flanges some of the arms and theresilient parts are positioned to engage a side of the support structurewhich is transverse to the rails, and wherein the means for demountablysecuring the base to the support structure cooperate with said lastmentioned arms and the support structure.

References Cited UNITED STATES PATENTS ROBERT M. WALKER, PrimaryExaminer US. Cl. X.R.

